Study design
CMV prophylaxis was assessed in a randomised, multi-centre, double-blind, placebo-controlled, pivotal, Phase 3 study of adult CMV-seropositive recipients (R+) of an allogeneic HSCT (haematopoietic stem cell transplant).a Subjects were randomised (2:1) to receive either PREVYMIS or placebo and stratified by investigational site and risk (high vs. low) for CMV reactivation at the time of study entry (n=565).1
Median time to randomisation was 9 days after transplantation.1
aFull analysis set included randomised subjects who received at least 1 dose of study medicine and excluded subjects with detectable CMV DNA at baseline.1
Additional study design details
- The protocol suggested thresholds for the initiation of pre-emptive therapy were >150 copies/mL for high-risk patients and >300 copies/mL for low-risk patients through Week 14 post-transplant and a threshold of >300 copies/mL for all patients thereafter6
-
Patients were considered high risk if they met 1 or more of the following criteria:1
- Human leukocyte antigen (HLA)-related (sibling) donor with at least 1 mismatch at 1 of the following 3 HLA-gene loci: HLA-A, -B, or -DR
- Haploidentical donor
- Unrelated donor with at least 1 mismatch at 1 of the following 4 HLA-gene loci: HLA-A, -B, -C, or -DRB1
- Use of umbilical cord blood as the stem cell source
- Use of ex vivo T cell–depleted grafts
- Grade 2 or greater GVHD, requiring systemic corticosteroids
Efficacy endpoints
The primary end point was defined as the proportion of patients with clinically significant CMV infection at Week 24.1
For the primary end point, patients were also considered failures of CMV prophylaxis if they:
- Discontinued from the study prior to Week 24 post-transplant
- Were missing an outcome at Week 24 post-transplant
Results
PREVYMIS demonstrated superior efficacy over placebo in the primary end point: the proportion of patients with clinically significant CMV infection at Week 24.1,a

Adapted from PREVYMIS Summary of Product Characteristics1
aClinically significant CMV infection was defined as the incidence of CMV viraemia warranting anti-CMV pre-emptive therapy or the occurrence of CMV end-organ disease.1
- The treatment difference was driven by clinically significant CMV infection, with otherwise similar proportions of patients who discontinued the trial or with missing outcomes1
Adverse events
PREVYMIS demonstrated a generally well-tolerated safety profile for adult allogeneic HSCT (haematopoietic stem cell transplant) CMV (cytomegalovirus) prophylaxis.1
Overall incidence of adverse events (AE) was comparable to that in the placebo group.1
AEs reported in ≥1% of patients and at a frequency greater than placebo.7
AE | PREVYMIS (n=373) | Placebo (n=192) |
---|---|---|
Nausea | 7.2% | 3.6% |
Diarrhoea | 2.4% | 1.0% |
Vomiting | 1.9% | 1.0% |